1. Field of the Invention
This invention relates to a method and an apparatus for image processing and, more particularly, to a method and an apparatus for image processing capable of processing an image signal in each of a plurality of processing modes.
2. The Prior Art
A conventional image processing apparatus is known which generally consists of a memory and an interface and which effects processing for inputting an image from an external unit or outputting an image to the external unit. For example, this apparatus is used in combination with a reader, a printer or the like in such a manner as to output an image read by the reader to an external unit or output by a printer an image which is transferred from an external unit.
Such an image processing apparatus requires being adaptable to a printer having a printing process as shown in FIG. 12. FIG. 12 shows an ink jet head unit 400, a rail 401 on which the unit 400 moves, and a recording sheet 402. The ink jet head unit 400 is driven by a driving unit (not shown) to scan from the left to right as viewed in FIG. 12 to output an one-line image. "One-line image" denotes an image formed on the recording sheet by one cycle of scanning of the ink jet head unit 400. Accordingly, "one-line image" as hereinafter referred to in this specification denotes an image or image data formed by one cycle of scanning of a recording head provided in a printer.
After a one-line image has been output, the recording sheet 402 is transferred upward as viewed in FIG. 12 (in the direction of the arrow) to an extent corresponding to one line, while the head unit 400 moves on the rail 401 to return to the left end position. This process is repeated to form the entire image.
A printer having such a process is characterized such that the printing process can be stopped each time one head scanning cycle is completed. In a case where this printer is operated in association with the above-mentioned image processing apparatus, a process may be adopted such that a one-line image signal is written in a memory from the outside and is output, and another one-line image signal is transferred from the outside to the memory after the outputting of the former signal has been completed, to enable an image output having an amount of data exceeding the memory capacity.
Although an apparatus operating in a mode of repeating processing by reading one-line image data and outputting the data for printing (hereinafter referred to as "line data sequential processing") can process a large amount of image data which exceeds the memory capacity, it cannot be adapted to editing processing, including registration of the entire image data in the memory or modifying a registered image layout.
Also, the apparatus cannot be applied to processing image data in which R, G and B color components are expressed by multi-value data, and the data is entirely transferred to a frame memory and developed with respect to each color (which processing is hereinafter referred to as "frame data sequential processing").